Blade lock pin retainer



May 2, 1961 A. HUNT, JR

BLADE LOCK PIN RETAINER 2 Sheets-Sheet 1 Filed Jan. 28, 1959 ATTORNEY A. L. HUNT, JR

BLADE LOCK PIN RETAINER Filed Jan. 28. 1959 2 Sheets-Sheet 2 ATTORNEY United States Patent BLADE LOCK PIN RETAINER Albert Lowrie Hunt, Jr., Indianapolis, Ind., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Jan. 28, 1959, Ser. No. 789,647

7 Claims. (Cl. 253-77) 7 X My invention is directed to improvements in means for retaining removable blades on the rotors of turbomachines such as axial-flow compressors and turbines, for example.

Such machines as axial-flow compressors quite commonly comprise a rotor made up of a number of disks, the rims of which have generally axially extending slots in which blades are mounted with a dovetail engagement. A means which has been employed to hold the blade root in the slot is a pin inserted in the rim of the rotor and engaging in a notch in the blade root. My invention is concerned with the addition to such structure of a readily applied and removed and simple retaining means which will hold the pins in place in the holes in the rotor when the rotor is assembled. In its preferred form, the pin retaining means comprises a split expanding resilient ring mounted inside the rim of the rotor and engaging the radially inner ends of all of the pins to hold them against inward movement out of engagement with the notch in the blade root.

The principal objects of the invention are to provide a safeguard against release of any of the blade locking pins from the blades and to provied this with a simple, reliable, light weight and easily installed structure.

The nature of the invention and the advantages thereof will be clear to those skilled in the art from the accompanying detailed description of preferred embodiments of the invention and the accompanying drawings thereof.

Figure 1 is a partial rear elevation view of a single stage of a compressor rotor.

Figure 2 is an enlarged fragmentary view of a blade pin locking ring taken on the plane indicated by the line2--2 in Figure 1.

Figure 3 is an enlarged partial sectional view taken on the plane indicated by the line 3 3 in Figure 1.

Figure 4 is a view similar to Figure 1 of a second species of the invention.

Figure 5 is a fragmentary view taken on the plane indicated by the line 5-5 in Figure 4.

, Figure 6 is a sectional view taken on the plane indicated by the line 6-6 in Figure 4.

The invention is illustrated herein as incorporated in the first stage of a compressor rotor of knowntype illustrated and described in US. Patents 2,675,174 and 2,800,-

273. The details of the compressor rotor, except as described herein, are immaterial to the invention, and it is deemed unnecessary to illustrate or describe in detail the known structure or" the rotor.

The rotor comprises a first stage rotor member 9 which comprises a wheel or disk 10 having a rim or flange 11 in which are machined a number of undercut slots 12 extending generally axially of the rotor. The rotor member 9 is illustrative of various forms of rotor members to which the invention is applicable. A number of blades 13 are mounted on the rotor, each blade including a root 14 configured for dovetail engagement in one of the slots 12 of the rotor member. Blade locking pins 16 extend through holes 17 in the 1im 11 from the radially inner surface 18 thereof into each slot 12, which is cut inithe radially outer surface 19 of the rotor member. The pins 16 may be of any desired type and, as illustrated, are hollow pins of the type known commercially as rollpins. Each blade root is machined to provide a notch 21, the forward and rear faces 22 and 23 of which define abut-. .rnents which cooperate with the pin 16 to hold the blade root against sliding out of the slot 12.

By way of background, it may be pointed out that pins of this sort cooperating in this way with the rotor and with the blade roots have been known previously, but prior art structures have presented difliculties in retaining the pins 16 surely with any structure which makes it easy to remove the pins when necessary to replace a blade. For reasons which are not entirely clear, and which may be the result of vibration or heating and cooling, the pins may become loose in the holes and fall out of the rotor member when the compressor is not rotating. In normal operation of the compressor, the pins are held in place by centrifugal force. It has been found that even the resilient hollow pins of the type known as rollpins on occasion become loose and drop out of the holes in the rotor, or back off sufficiently to release the blade.

My invention provides a very simple and reliable retaining means for the pin 16. As illustrated in Figures 1 to 3, the retainer is a resilient expanding split ring 25 preferably made of stainless steel or similar metallic material. The ring is generally of channel section, comprising a base 26 and radially extending flanges 27 and 28. The base 26 lies inside the inner ends of the pins and either engages the pins or is in close proximity to them,

so" that it must be contracted to install it and its resilience biases the ring outwardly at all times.

It will benoted that the flange 27 lies adjacent the forward edge of the blade locking pin 16 and the flange 28 lies behind each blade locking pin. In order to provide most accurate radial location'of the ring 25 so as to prevent interference with balance of the rotor, it is desirable that one flange engage the rotor. In the form of Figure 3, the rear flange 28 extends outwardly beyond the forward flange 27 and engages the inner surface 18 of the rotor.

It is desirable to provide means to lock or restrain the ring against rotation around the axis of the compressor.

These lie on opposite circumferential sides of one of the pins 16 and prevent any significant circumferential shift ing of the ring 25. As will be apparent, the ring 25 provides a constant resilient bias which is quite adequate to prevent any of the pins 16 from dropping out of the engaged position even though they should become loose.

To install the ring, it may be contracted, with the ends slightly overlapping, so that the flange 27 will clear the inner ends of the pins 16 and then be moved into position underlying the pins, whereupon it is released and allowed to expand into engagement with the rotor. The tabs 31 and 32 are engaged on opposite sides of oneof the pins 16 at this time. The ring may be removed by reversing this procedure, after which any or all of the pins may be removed by pliers on other suitable means.

The form of the invention shown in Figures 4 to 6 is quite similar to that previously described and, so far as the parts are the same, they are identified by the same reference numbers as those previously applied. The difference lies in the structure of the retaining ring identified as 50. Ring 50 includes a base portion 51 and flanges 52 and 53. In this case, the flanges are of equal dimensions, and the forward flange 52 engages the inner surface 18 of the rotor and the forward portion of the rollpins 16. The structure for holding ring 50 against rotation in this case comprises tabs 56 and 57 bent inwardly from the flanges 53 and 52, respectively, so as to lie on opposite circumferential sides of a pin 16. As w1ll be apparent, the retaining ring of Figures 4 to 6 is installed and removed in the same manner and works in the same way as that of Figures 1 to 3.

The simplicity, lightness and inherent reliability of the structures described will be apparent. The provision of some such structure is highly desirable in view of the serious consequences of release of the blades from the rotor and the desirability of providing some securing means for the blade lock pins which is reliable and easy to intsall and remove. In this connection, pins have been retained in the prior art by such expedients as making the pin short enough to terminate within the hole 17 and peening over the surface of the rotor to retain the pm. This is time-consuming and makes it diflicult to remove the pin.

The detailed description of preferred embodiments of the invention for the purpose of explaining the principles nular rotor member having radially outer and inner surfaces, an annular row of blades mounted on the rotor, the rotor member having undercut blade slots in its outer surface directed generally axially of the rotor member and the blades having roots slidably mounted in the slots with dovetail engagement therein, the rotor member having generally radial holes extending from its inner surface into the blade slots, and the blade roots defining abutments located to cooperate with a pin inserted through a said hole to lock the blade in the slot, a pin inserted through each hole cooperating with the said abutments and extending from the inner surface of the rotor member; and means for retaining the pins in the holes comprising a resilient expanding ring extending around the inner surface of the rotor member adjacent the inner ends of the pins, the ring having outwardly extending .flanges embracing the portion of the pins extending from the rotor member to locate the ring axially of the rotor member.

2. A turbomachine comprising, in combination, an annular rotor member having radially outer and inner surfaces, an annular row of blades mounted on the rotor,

the rotor member having undercut blade slots in its outer surface directed generally axially of the rotor member thereof is not to be considered as limiting or restricting and the blades having roots slidably mounted in the slots 'with dovetail engagement therein, the rotor member hav-"- .ing generally radial holes extending from its inner cur face into the blade slots, and the blade roots defining abutments located to cooperate with a pin inserted through a said hole to lock the blade in the slot, a pin inserted through each hole cooperating with the said abutments and extending from the inner surface of the rotor member; and means for retaining the pins in the holes comprising a resilient expanding ring extending around the inner surface of the rotor member adjacent the inner ends of the pins, the ring having outwardly extending flanges embracing the portion of the pins extending from the rotor member to locate the ring axially of the rotor member, one of said flanges being in engagement with the inner surface of the rotor member in the normal installed position of the ring.

3. A turbomachine comprising, in combination, an annular;rotor memberhaving radially outer and inner surfaces, an annular row of blades mounted on the rotor, the rotor member having undercut blade slots in its outer surface directed generally axially of the rotor member and the blades having roots slidably mounted in the slots with dovetail engagement therein, the rotor member having generally radial holes extending from its inner surface into the blade slots, and the blade roots defining abutments located to cooperate with a pin inserted through a said hole to lock the blade in the slot, a pin inserted through each hole cooperating with the said abutments and extending from the inner surface of the rotor member; and means for retaining the pins in the holes comprising a resilient expanding ring extending around the inner surface of the rotor member adjacent the inner ends of the pins, the ring having outwardly extending flanges embracing the portion of the pins extending from the rotor member to locate the ring axially of the rotor member, the ring having means connected to the rotor member to hold the ring against rotation relative to the rotor member; one of said flanges being in engagement with the inner surface of the rotor member in the normal "installed position of the ring.

with dovetail engagement therein, the rotor member having generally radial holes extending from its inner surface into the blade slots, and the blade roots defining abutments located to cooperate with a pin inserted through a said hole to lock the blade in the slot, a pin inserted through each hole cooperating with the said abutments and extending from the inner surface of the rotor member; and means for retaining the pins in the holes comprising a resilient expanding ring extending around the inner surface of the rotor member adjacent the inner ends of the pins, the ring having outwardly extending flanges embracing the portion of the pins extending from the rotor member to locate the ring axially of the rotor member, the ring having means extending outwardly therefrom in position to engage circumferentially opposite sides of one pin to hold the ring against rotation relative to the rotor member.

5. A turbomachine as recited in claim 4 in which the means extending outwardly from the ring is provided by tabs extending from the portion of the ring between the flanges.

6. A turbomachine as recited in claim 4 in which the means extending outwardly from the ring is provided by tabs. extending from the flanges of the ring.

7. A turbomachine comprising, in combination, an annular rotor member having radially outer and inner surfaces, an annular row of blades mounted on the rotor, the rotor member having undercut blade slots in'its outer surface directed generally axially of the rotor member with dovetail engagement therein, the rotor member having generally radial holes extending from its inner surface into the blade slots, and the blade roots defining abutments located to cooperate with a pin inserted through a said hole to lock the blade in the slot, a pin inserted through each hole cooperating with the said abutments and extending from the inner surface of the rotor memher; and means for retaining the pins in the holes comprising a resilient expanding ring extending around the inner surface of the rotor member adjacent the inner ends of the pins, the ring having outwardly extending flanges embracing the portion of the pins extending from the rotor member to locate the ring axially of the rotor member, the ring having means extending outwardly therefrom in position to engage circumferentially opposite sides of one pin to hold the ring against rotation relative to the rotor member; one of said flanges being in 'engagement with the inner surface of the rotor inember in the normal installed position of the ring.

References Cited in the file of this patent UNITED STATES PATENTS 

